Folding knife



FIG. 1 is a front elevational view of a folding knife showing my new design, in an open state;

FIG. 2 is a top plan view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is a left side elevational view thereof;

FIG. 6 is a right side elevational view thereof; and

FIG. 7 is a front elevational view thereof, in a closed state. 

The ornamental design for a folding knife, as shown and described. 